Electric heating element



Nov. 10, 1959 v R. H. BALESTRINI 2,912,661

ELECTRIC HEATING ELEMENT Filed Feb. 14, 1957 2 Sheets-Sheet 1 rum FIG.

IN VEN TOR.

NOV. 10, 195 v R. H. BALESTRINI 2,912,661

ELECTRIC HEATING ELEMENT United States Patent ELECTRIC HEATING ELEMENT Roberto Horacio Balestrini, Buenos Aires, Argentina Application February 14, 1957, Serial No. 640,130

Claims. (Cl. 338-58) The invention relates to a heating element of the type having a resistor mounted between supporting elements made of dielectric material. An essential feature of the invention is that the heating element resistor consists having a band of a rectangular shape and having a thickness which virtually is within the range of a thin film.

A heating element with a resistor having a shape mentioned in the preceding paragraph offers a means for radiating rays of a high power, accompanied by infra-red rays, virtually instantaneously and suspectible of being produced at the very moment of connecting said heating element with the socket of the supply line of the electric current.

This result is accomplished by the reduced thickness of the band which forms the resistor which causes the rapid heating thereof to red-hot, and such a band has a greater radiation surface than an equal volume of threads of a round profile, helically wound up upon conventional resistors.

On the other hand, considering that the band is apt to be mounted upon a supporting frame without forming a helical winding it is possible to obtain a heating element of a great power with the use of only a small amount of material for forming the resistor as compared with the amount of material required for present resistors consisting of a helical winding.

The formation of the heating element by means of a band as above described presents the problem of neutralizing the expansion to which the band is exposed due to heating. The solution of this problem forms one of the distinctive characteristics of the element in question, as the solution of the stated problem is based upon maintaining the band in a normal tension and counterbalancing the expansion by mounting said element upon two rollers which act as supporting means, and have upon their surface a plurality of circular grooves which are distributed along said rollers. Said grooves form the mounting zones of the band which has the shape of a helical winding.

The rollers which act as a supporting frame for the band act at the same time as a means for maintaining in constant tension the straight sections which form the different sheathings of the band formed by its passage over the rollers in constant tension. One of the rollers is movable with relation to the other one which latter acts as a stationary unit.

For the very reason that one of the rollers is movable with relation to the other one, the first one acts as an but avoiding furthermore the possibility of contact between the sheathings which would cause over-heating and a breakage of the band for reasons which are well known.

In accordance with what has been explained in the preceding paragraph, one of the rollers is movable with relation to the other one, and for this purpose it is provided with means which are capable of maintaining it in a state of constant tension with a tendency to cause the further stretching thereof while the band is expanding, thus counterbalancing the expansion efiects.

Broadly stated therefore, the present invention contemplates a heating element which comprises a band of conductive material, of rectangular shape and of a thickness which is virtually equivalent to that of a thin film; a supporting frame for the band, composed of two rollers separated from one another, upon which the band will be.

placed in helical sections, and resilient means for one:

of said rollers so that the bands tend to be taut counterbalancing the expansion thereof when heated.

The heating element will now be described in detail with:

particular reference to the accompanying drawingswherein:

Figure l is a transversal side view of the device on line: 1-1 of Fig. 2;

Figure 2 illustrates a bottom View of the device taken: on line 2-2 of Fig. 1;

Figure 3 is a top view showing a different embodiment of the device.

Figure 4 shows the device illustrated in Fig. 3 in a view similar to Fig. l.

in these views the same reference numbers and letters indicate the same or corresponding parts.

Heating element a to which the present invention relates will be described with reference to Figures 1 and 2 of the accompanying drawings and consists of a band made of good conductive material, of rectangular shape and of a thickness which is virtually equivalent to that of a thin film. Said band is Wound in helical sections which are held at their extremes in circular grooves 2 and 3 arranged upon respective supporting rollers 4 and 5 of a dielectric material which rollers constitute the supporting frame of said band.

Roller 4 is a stationary unit fixed to support 6, whereas roller 5 is a movable unit which is joined by an element to the free end 7 of the arm 8 of a lever of the third class said arm 8 which ends as a bent portion 8 is united to support 9 which supports the lever in question.

Figures 3 and 4 show a different embodiment of the heating element wherein, in addition to the heating element a described with reference to Figures 1 to 2 there is a second heating element b. Thus heating element a comprises the band of good conducting material 1, wound to helical sections to circular grooves 2 and 3 of rollers 4 and 5 which form the supporting frames of the band. Heating element b comprises band 11 which is similar to band 1, being also wound in helical sections to circular grooves 12 and 13 of respective rollers 14 and 15. Both expansion ofv the bands and maintaining them in con-- stant tension.

Although there has beendescribed in the embodiment of Figure 1 one heating element wound upon two supporting frames, it will be understood that one and the 7 same heating element may also be put upon a series of frames which follow one another in a polygonal order wherein the sides of the polygon are formed by sections wound helically between each contiguous pair of frames which form in themselves the tops of the sides. This disposition enables the formation of a heating surface which offers a large perimeter.

The heating element described with reference to the accompanying drawings clearly shows a means for getting a high heating effect by an ample heating surface oifered bythe band forming the resistor which acts as a heating unit. It is therefore apparent that further modifications of details can be made without departing from the spirit and scope of the claims.

I claim:

1. An electric resistance heating device, comprising, in combination, a pair of elongated insulator members spaced in parallel relationship; a length of an easily bendable resistor band having Wide side faces of a width much greater than the thickness of said band and wound flatwise spirally over both insulator members with the windings spaced from one another and so arranged that the intermediate straight portions of the windings extending between the two insulator members present outwardly said wide. side faces edgewise adjacent to one another; terminal means carried by at least one of said insulator members connected to respective ends of said resistor band; a pair of supporting structures for the respective insulator members, one of said structures having bracket means and a swingable member pivotally mounted on said bracket means and connected to the associated insulator member supporting the same movably to vary the distance between the insulator members to allow for variations in the length of said intermediate band portions due to thermal expansion and contraction; and spring means eifective between said bracket means and said swingable member effective to permanently urge the associated insulator member away from the opposite insulator member.

2. An electric resistance heating device, comprising, in combination, a pair of elongated insulator members spaced in parallel relationship; a length of an easily bendable resistor band having wide side faces of a width much greater than the thickness of said band wound flatwise spirally over both insulator members with the windings spaced from one another and so arranged that the intermediate straight portions of the windings extending between the two insulator members present outwardly said wide side faces edgewise adjacent to one another; terminal means carried by at least one of said insulator members connected to respective ends of said resistor band; a pair of supporting structures for the respective insulator members, one of said structures having bracket means and a swingable member pivotally mounted on said bracket means and connected to the associated insulator member supporting the same movably to vary the distance between the insulator members to allow for variations in the length of said intermediate band portions clue to thermal expansion and contraction; and tension spring means eifective between said bracket means and said swingable member effective to permanently urge the associated insulator member toward said bracket means and away from the opposite insulator member.

3. An electric resistance heating device, comprisingin combination, a pair of elongated insulator members spaced in parallel relationship; a length of easily bendable resistor band having wide side faces of a Width much greater than the thickness of said band wound flatwise spirally over both insulator members with the windings spaced from one another and so arranged that the intermediate straight portions of the windings extending between the two insulator members present outwardly said wide side faces edgewise adjacent to one another and extending in planes parallel to a reference plane; terminal means carried by at least one of said insulator members connected to respective ends of the resistor band; supporting means arranged to extend in one direction from said reference plane for supporting theone insulator member spaced relative thereto; bracket means arranged to extend'in the opposite direction from said reference plane with a swingable member pivotally mounted on said bracket means and arranged to extend through said reference plane and connected to the other insulator member supporting the same movably to vary the distance between both insulator members allowing for variations in the length of said intermediatebandspaced in parallel relationship, with one insulator member of one unit arranged parallel and adjacent to one insulator member of the other unit to constitute a pairof inwardly disposed insulator members located intermediate the respective opposite insulator members; a

length of easily bendable resistor band having wide side faces of a width much greater than the thickness of said band wound flatwise spirally over both insulator members with the windings spaced from one another and so arranged that the intermediate straight portions of the windings extending between the two insulator members present outwardly said wide side faces edgewise adjacent to one another and extending in planes parallel to a reference plane, terminal means carried by at least one of said insulator members, a pair of supporting structures arranged to extend in one direction from said reference plane for supporting the respective opposite insulator members spaced from said plane, bracket means arranged to extend relative to said reference plane in the opposite direction from said pair of supporting structures, with a pair of swingable members pivotally mounted on said bracket means and arranged to extend.

through said reference plane and connected to respective inner insulator members supporting the same movable to vary the respective distances between the inner insulator member and the associated outer insulatormem ber allowing for variations in the length of the respective intermediate band portions of the heating units due to' thermal expansion and contraction; and spring means acting between said swingable members and disposed with respect to said reference plane opposite to said re-- slstor windings, said spring means being effected to urge 1 the associated inwardly disposed insulator members away from their respective opposite insulator members.

5. An electric resistance heating device comprising, in combination, a heating unit having a pair of elongated.

insulator members spaced in parallel relationship; a length of an easily bendable resistor band having wide side faces of a width much greater than the thickness of said bandv and wound fiatwise spirally over both insulator members Wltll 'tl'le windings spaced from one another and. so. ar-.

ranged that the intermediate straight portions of the windings extending between the two insulator members present outwardly said wide side faces edgewise adjacent to one another; terminal means carried by at least one of said insulator members connected to respective ends of said resistor band; a housing surrounding said heating unit and having an aperture exposing said unit for the emission of heat therefrom through said aperture; a supporting structure for one of said insulator members disposed within and carried by said housing; movable means supporting the other insulator member carried by said housing and extending from said insulator member outwardly through the wall of said housing, and arranged to be movable for varying the distance between the insulator member; and spring means disposed outwardly of said housing and acting upon said movable means to permanently urge the associated insulator member away from the opposite insulator member.

Youmans June 17, 1913 Du Bois Ian. 5, 1954 

